Apparatus for the production of non-woven net fabrics

ABSTRACT

An improved apparatus for forming textile non-woven net fabrics composed of a sheet of weft threads adhesively secured to one or more sheets of warp threads, the weft sheet being formed by continuously winding a thread about a pair of spaced thread supporting screws to form a plurality of reaches therebetween, and wherein the screws are rotated about their longitudinal axes such that the helically threaded surface of the screws support the loop ends of the thread reaches to laterally advance the reaches in spaced relation along the screws to form the weft sheet.

M. M.BOLLE S APPARATUS FOR THE PRODUCTION OF NON-WOVEN NET FABRICS April 17, 1973 2 Sheets-Sheet 1 Filed Feb. 10, 1969 :2 I4 /58 7 53-46 40 no 98 FIG.

I INVENTOR.

' MILTON M. BOLLES ATTORNEY 'April 17, 1973 BOLLES 3,728,195

APPARATUS FOR THE PRODUCTION OF NON-WOVEN NET FABRICS Filed Feb. 10, 1969 2 Sheets-Sheet 2 I 9 2\\ F'/6. -3- i INVENTOR. MILTON B OLLES ATTORNE United States Patent 3,728,195 APPARATUS FOR THE PRODUCTION OF NON-WOVEN NET FABRICS Milton M. Bolles, Spartanhurg, S.C., assignor to Deering Milliken Research Corporation, Spartanburg, S.C. Filed Feb. 10, 1969, Ser. No. 798,044 Int. Cl. D04h 3/04 US. Cl. 156-441 2 Claims ABSTRACT OF THE DISCLOSURE An improved apparatus for forming textile non-woven net fabrics composed of a sheet of weft threads adhesively secured to one or more sheets of warp threads, the weft sheet being formed by continuously winding a thread about a pair of spaced thread supporting screws to form a plurality of reaches therebetween, and wherein the screws are rotated about their longitudinal axes such that the helically threaded surface of the screws support the loop ends of the thread reaches to laterally advance the reaches in spaced relation along the screws to form the weft sheet.

This invention relates to the production of textile fabrics and, more particularly, to an improved apparatus for the formation of non-woven net fabrics. These fabrics are widely used as reinforcement in various laminated products, such as synthetic polymeric films, paper sheets, and the like, and as a support backing for carpets and multi-part materials, such as ceramic or wooden floor tiles. Such fabrics are also useful as packing materials, and as screening material for windows, doors and the like.

In French Pat. No. 1,208,968 there is disclosed a process and apparatus for the production of textile non-woven net fabrics wherein one or more continuous threads are wound about a pair of spaced elongate thread support bars in a plurality loops or reaches. The reaches are moved laterally along the bars to form a weft sheet by frictional engagement of the loop ends of the reaches with moving selvage threads disposed therebetween. One or more sheets of warp threads are brought into contiguous co planar relation with the moving weft sheet by passing the sheets through a pair of nip rolls and the combined sheets are adhesively secured together to form a composite non-woven net fabric. Due to variations in the frictional surface characteristics of the selvage threads as well as variations in the tension and speed of movement of the selvage threads during the formation of the weft sheet, it is difiicult in the aforementioned apparatus to insure uniform lateral movement and uniform spacing of the weft thread reaches in the weft sheet, resulting in the production of non-uniformly constructed net fabrics.

In French Addition Pat. No. 79,765 to the above-mentioned patent, and in US. Pat. 3,422,511, the disclosures of both of which are incorporated herein by reference, there are disclosed improved apparatus for forming the non-woven net fabrics wherein the weft sheet is formed by the use of a rotating tubular thread guide arm which winds a continuous thread about a pair of spaced thread support members consisting of helical springs, each of which is supported at one end for rotation about its central axis. The springs are disposed in generally parallel relation, and, as the continuous thread is wound or looped about the supported ends of the springs to form a plurality of thread reaches therebetween, the end portions of the thread reaches fall between the helices of the springs. As the springs rotate, the helices supportably engage consecutive loop ends of the reaches to laterally advance the reaches along the springs in spaced relation to form the weft sheet.

Although the helical support springs provide means 3,728,195 Patented Apr. 17, 1973 "ice for more positively advancing the weft threads in spaced relation to form the weft sheet, the use of the springs has certain disadvantages. Due to the long extent and relatively flexible nature of the end-supported springs, the springs are easily displaced from their proper parallel relationship during rotation, being readily pulled inwardly towards each other to cause undesirable width variations in the weft sheet. In addition, at the high rotational speeds desired for economical commercial production of the fabric, the springs tend to vibrate which often causes misplacement of the thread reaches between the helices of the springs and resultant non-uniform spacing of the reaches in the weft sheet. Since the distance between the weft threads, and thus the resultant density of the fabric, is determined by the thickness of and the distance between the adjacent helices of the springs, it is difficult to produce high density fabrics with the springs. Because of the relatively long length and thin construction of the springs which are necessary to produce dense fabrics, such springs are extremely weak and are easily broken during use. It is therefore an object of the present invention to provide an improved apparatus for prducing non-woven net fabrics which overcomes the problems of the prior art.

It is a further object of the present invention to provide an improved apparatus for producing non-woven net fabrics which can be readily employed to produce a wide range of fabric constructions at increased operational speeds and with uniform placement of the weft threads therein.

It is a further object to provide an apparatus of the type described wherein the left sheet forming means thereof is of high strength, durable construction, and may be maintained in proper position at all times during its rotation to provide a uniform weft thread sheet.

The above as well as other objects of this invention are accomplished by providing an apparatus for producing non-woven net fabrics wherein the spaced rotatable support members for forming the weft sheet comprise a pair of elongate screws of highly rigid construction, and wherein the screws are supported at one end for rotation about their longitudinal axes while their threaded surfaces engage loop ends of the thread reaches extending therebetween to advance the thread reaches in uniformly spaced relation to form the weft sheet. More specifically, the screws of the present invention possess a high section modulus such that they resist displacement from their longitudinal axis to exhibit exceptional positional stability during rotation. The threaded surfaces of the screws also can be readily constructed and configured to more closely position the weft threads in the weft sheet to obtain any desired density level of weft threads in the net fabric product. In addition, the thread supporting screws of the present invention may be constructedw ith a relatively large cross-sectional configuration at their rotata'bly supported ends to provide additional strength and rotational stability, while being tapered toward their open or thread discharge ends to bring the thread reaches of the weft sheet into a substantially co-planar relation before combining with the warp sheets.

Details of the invention will be further explained and more fully understood by reference to the accompanying drawings, in which;

FIG. 1 is a schematic side elevation of an apparatus for producing non-woven net fabrics embodying the features of the present invention;

FIG. 2 is a schematic plan view of the apparatus of FIG. 1, with portions of warp sheet path shown in FIG.- 1 omitted for convenience; and

FIG. 3 is an enlarged sectional view taken generally along line 3-3 of FIG. 2, and showing in more detail, one of the rotatable thread support screws of the apparatus.

- Referring more particularly to the drawings, FIG. 1 shows an apparatus for continuously forming non-woven net fabrics which generally includes a thread winding section 10, a weft sheet forming section 12, a warp and Weft sheet combining section 14, and a section, indicated at 16, for securing the sheets in contiguous co-planar relation to form a non-woven net fabric.

As shown in FIGS. 1 and 2, thread winding section includes thread winding means comprising a hollow tubular thread-guide arm 20 secured to a hollow central shaft 22 for rotation therewith. Shaft 22 is suitably supported, as by a support frame 23, for rotation about its central axis and is rotatably driven by a motor 24, the shaft 25 of which is drivingly connected thereto by sprockets 27, 28 and an endless drive chain 29 (shown in broken lines). Guide arm 20 is appropriately counterbalanced for rotation by a weighted arm 30. During rotation of thread guide arm 20, a continuous thread 32 is continuously passed from a thread supply package 34 through the hollow shaft 22, radially outwardly through the hollow tubular arm 20, and through a thread outlet 26 in its outer end.

The weft sheet forming section 12 includes a pair of spaced thread support members 40, 42 which supportably receive the thread 32 passing from the outlet 36 of guide arm 20 in a plurality of generally parallel thread reaches R therebetween (FIG. 2). Thread support members 40, 42 are of substantially identical construction and are best described by reference to FIG. 3, which is an enlarged elevational view of the rotatable member 40. Each rotatable member comprises an elongate screw 44 having a helically threaded surface extending throughout a major portion of its length. The screw is constructed of high strength, rigid material, such as steel, aluminum, plastic, or the like, and one end thereof is removably secured, as by a set screw 45, in the enlarged end portion of a stub shaft 46 for rotation therewith. The stub shaft 46 is retatably mounted on the end of a cross-arm 48 which is supported by a bearing 49 surrounding the drive shaft 22. Each thread support screw is rotated about its longitudinal axis by a sprocket chain 50 drivingly connecting a sprocket 51 on the end of drive shaft 22 to sprockets 53, 54 on the respective stub shafts 46, 47. To facilitate positional support of the screws, suitably supported blocks or stop members 56, 57 are positioned beneath each screw and abuttingly engage the same to prevent rotation of the cross-arm 48 and screws about the shaft 22 during its rotation and thereby positionally stabilize the same.

As best shown in FIG. 3, the shaft-supported end portion of each screw is of relatively large cross section to provide maximum strength and rigidity to the screw during its rotation by the stub shaft. The screw preferably is tapered along its length in the direction of advancement of the thread reaches thereon to bring the upper and lower reaches of the thread loop ends progressively towards each other during their advance along the screws, such that the weft sheet reaches approach co-planar alignment as they enter the warp and weft sheet combining section 14 of the apparatus. Note the position of loop end portions of the continuous weft thread 32 in the grooves of the screw 44 shown in FIG. 3. The taper of the thread supporting screws also serves to relieve any tension which may be imposed on the thread reaches during the winding of the thread on the screws and which might tend to cause misplacement of the reaches in the weft sheet as the reaches leave the ends of the screws.

The ends of the screws adjacent the stub shafts 46, 47 may be provided with conically shaped thread guides 58, 59 which facilitate placement of the thread reaches in the thread grooves of the screws as they are wound thereon by the guide arm 20.

As best seen in FIGS. 1 and 3, the warp and weft sheet combining section 14 includes a pair of nip rolls 84, 86 which are rotatably supported by suitable means, not shown, between the free or open ends of the screws. As

seen in FIG. 3, as the screws rotate to advance the thread reaches in spaced, parallel relation therealong to form the weft sheet; the thread reaches leaving the open ends of the screws pass between and are engaged by nip rolls 84, 86. One or more sheets 90, '92 of warp threads are supplied continuously to the nip portion of the rolls 84, 86 from a suitable source, not shown, and, during their movement therethrough, the warp and weft sheets are brought into contiguous co-planar relation. The loop ends of the weft thread reaches are released from the rotating support screws and the combined sheets pass over a guide roller 98 to the sheet securing section 16.

The securing section 16 includes an adhesive bath 100 through which the composite sheet of warp and weft threads are passed by rotatable squeeze rolls 102, 103 to apply a suitable adhesive thereto. The sheet thereafter passes about the surface of heated drying rolls 104, 105 where the warp and weft sections thereof are secured together, and the thus formed non-woven net fabric is collected on a collection roll 106. Although not shown, one or more of the rolls in the securing section 16 may be suitably driven to move the warp and weft sheets through the apparatus.

As best seen in FIGS. 2 and 3, the stub shafts 46, 47 and their respective thread supporting screws have aligned central passageways (note the screw passageway 108 shown in broken lines in FIG. 3) through which selvage threads 110, 111 continuously pass during formation of the weft sheet to be positioned within the loop ends of the weft thread reaches as the reaches leave the open ends of the screws. The selvage threads not only strengthen the composite non-woven net fabric product, but provide additional support to the weft sheet during its passage through the securing section 16 of the apparatus.

The threads which may be employed to form the nonwoven net fabrics may be composed of any continuous filament or spun textile yarns of synthetic or natural fiber composition. Where high strength is desired in the fabric product, as when the non-woven fabrics are to be employed as a reinforcement fabric in a composite product, mineral fibers, such as fiber glass threads, may be particularly desirable for use.

From the foregoing drawings and detailed description of the invention, it can be seen that the rigid screw support members of the present apparatus possess exceptional strength and rigidity so as to facilitate positive positioning of the screws during rotation, thereby insuring uniform placement of the reaches in the weft sheet and uniform width control of the sheet during high speed operation of the apparatus. In addition, the thread surfaces of the screws may be readily designed and constructed to uniformly position the weft thread reaches in closely spaced, even contiguous relation for the production of highly dense fabrics, without sacrificing the structural strength of the support members as has heretofore been the case when helical springs were employed. Depending upon the fabric construction desired, screws of various surface configurations may be readily interchangeably employed in the apparatus to produce non-woven net fabrics of exceptional quality and uniformity.

The foregoing drawings and specification have set forth a preferred embodiment of the invention and, although specific terms have been employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being limited only by the extent of the following claims.

That which is claimed is:

1. In an apparatus for producing non-woven net fabrics including means for winding a continuous thread about a pair of elongate, spaced, thread support members to form a plurality of reaches therebetween, the members being rotatable to advance the reaches laterally in spaced relation therealong to form a weft sheet, means for combining one or more sheets of warp threads with the sheet of weft threads in contiguous co-planar relation, and

means for securing the combined sheets together to form a non-woven net fabric; the improvement wherein each of said thread support members comprises a screw having a longitudinal passageway therethrough, the longitudinal axis of each screw extending generally parallel to the direction of advancement of said reaches, the grooves of the threaded surface of each screw being adapted to engage respective loop ends of the thread reaches to advance the reaches along the screw during its rotation, each screw being tapered over at least a portion of its thread-moving length in the direction of advancement of the reaches to move the respective thread reaches of each loop end toward each other and toward co-planar alignment during their movement along the screw, means rotatably supporting each screw at its larger end, and said means for combining one or more sheets of warp threads with the weft threads includes a pair of nip rolls extending between said screws, the smaller ends of said screws extending past the nip portion of said rolls in the direction of movement of the weft sheet to supportably guide the spaced reaches thereof into the nip portion for combining with the warp sheets.

2. Apparatus as defined in claim. 1 including means engaging the peripheral thread engaging surface of each screw adjacent its larger end to positionally stabilize the same during rotation.

References Cited UNITED STATES PATENTS BENJAMIN A. BO'RCHELT, Primary Examiner G. E. MONTONE, Assistant Examiner US. Cl. X.R. 28-72 NW zgjggg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 7 195 e v m April 17, 1973 Inventofls Milton 1168 It is certifiedthat error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In the specification, column l, line 37, after "plurality", insert --of parallel--.

Column 2, line 22, delete "prducing'l and insert --producing- Y 7 Column 2, line 31 delete "left" and insert --weft--. "Column 3, line 21, delete "26" and insert --36-.

Signed and sealed this 5th day of March 19714..

(SEAL)? I Attest:

C MARCHALL DANN- Commissioner of Patents EDWARD M.FLETCHER,JR. Attes ting Officer 

